| Abstract * |
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Recent advances in both, observational techniques and numerical simulations, have enabled us to detect a multitude of small-scale vortices in the solar atmosphere. Vortices are ubiquitous throughout the solar surface and at all layers of the solar atmosphere existing
over a wide range of spatial and temporal scales. Small-scale vortices are suggested to play an important role in the energy transport of the solar atmosphere, however, their physical properties remain poorly understood due to limited resolution. We explored the relationship between vortex flows at different spatial scales, analyze their physical properties, and investigate their contribution to Poynting flux transport from the lower to the upper layers of the solar atmosphere. Using three-dimensional (3D) radiative magnetohydrodynamic (MHD) simulation code 'MURaM', we perform numerical simulations of a unipolar solar plage region. For detecting and isolating vortices, we use 'Swirling Strength' criterion and select the locations where the fluid is rotating with an angular velocity greater than a certain threshold. We explore the spatial profiles of physical quantities viz. density, horizontal velocity, etc. inside these vortices. Moreover, to apprehend their general characteristics, a statistical investigation
is performed. We found that magnetic flux tubes have a complex filamentary substructure abundant of small-scale vortices (diameter ~50-100 km at the solar surface and ~100-200 km in the solar chromosphere). On their interfaces strong current sheets are formed that may dissipate and heat the solar chromosphere. Statistically, vortices have higher densities and higher temperatures than the average values at the same geometrical height. We also degrade
our simulation data to get an effective spatial resolution of 50 km, 100 km, 250 km, and 500 km, respectively. Analyzing simulation data at different effective resolutions, we found vortex flows existing over various spatial scales. In high-resolution simulation data, we detect
a large number of small-scale vortices. Whereas, in the degraded data with relatively poor resolutions, smaller vortices are averaged-out and larger vortices are detected. The Poynting flux over vortex locations is more than adequate to compensate for the radiative losses in the chromosphere indicating their possible role in the chromospheric heating. |
